Systems and methods for forming metal-containing layers using vapor deposition processes

ABSTRACT

A method of forming (and an apparatus for forming) a metal containing layer on a substrate, particularly a semiconductor substrate or substrate assembly for use in manufacturing a semiconductor or memory device structure, using one or more homoleptic and/or heteroleptic precursor compounds that include, for example, guanidinate, phosphoguanidinate, isoureate, thioisoureate, and/or selenoisoureate ligands using a vapor deposition process is provided.

BACKGROUND OF THE INVENTION

In integrated circuit manufacturing, microelectronic devices such ascapacitors are the basic energy storage devices in random access memorydevices, such as dynamic random access memory (DRAM) devices, staticrandom access memory (SRAM) devices, and ferroelectric memory (FERAM)devices. Capacitors typically consist of two conductors, such asparallel metal or polysilicon plates, which act as the electrodes (i.e.,the storage node electrode and the cell plate capacitor electrode),insulated from each other by a layer of dielectric material.

The continuous shrinkage of microelectronic devices such as capacitorsand gates over the years has led to a situation where the materialstraditionally used in integrated circuit technology are approachingtheir performance limits. Silicon (i.e., doped polysilicon) hasgenerally been the substrate of choice, and silicon dioxide (SiO₂) hasfrequently been used as the dielectric material with silicon toconstruct microelectronic devices. However, when the SiO₂ layer isthinned to 1 nanometer (nm) (i.e., a thickness of only 4 or 5molecules), as is desired in the newest micro devices, the layer nolonger effectively performs as an insulator due to the tunneling currentrunning through it.

Thus, new high dielectric constant materials are needed to extend deviceperformance. Such materials need to demonstrate high permittivity,barrier height to prevent tunneling, stability in direct contact withsilicon, and good interface quality and film morphology. Furthermore,such materials must be compatible with the gate material, electrodes,semiconductor processing temperatures, and operating conditions.

Additionally, as integrated circuit (IC) dimensions shrink, the abilityto deposit conformal thin films with excellent step coverage at lowdeposition temperatures is becoming increasingly important. Thin filmsare used, for example, in and/or for MOSFET gate dielectrics, DRAMcapacitor dielectrics, adhesion promoting layers, diffusion barrierlayers, electrode layers, seed layers, and/or for many other variousfunctions. Low temperature processing is desired, for example, to bettercontrol certain reactions and to prevent degradation of previouslydeposited materials and their interfaces.

High quality thin oxide films of metals, such as ZrO₂, Ta₂O₅, HfO₂,Al₂O₃, Nb₂O₅, and YSZ deposited on semiconductor wafers have recentlygained interest for use in memories (e.g., dynamic random access memory(DRAM) devices, static random access memory (SRAM) devices, andferroelectric memory (FERAM) devices). These materials have highdielectric constants and therefore are attractive as replacements inmemories for SiO₂ where very thin layers are required. These metal oxidelayers are thermodynamically stable in the presence of silicon,minimizing silicon oxidation upon thermal annealing, and appear to becompatible with metal gate electrodes. Additionally, Nb₂O₅, Nb₂O₅,La₂O₃, and/or Pr₂O₃ doped/laminated Al₂O₃, Ta₂O₅, and HfO₂ films havebeen shown to be useful for capacitor and gate dielectrics. Nb₂O₅doping/laminating has been shown to decrease leakage and stabilizecrystalline phases.

Efforts have been made to investigate various deposition processes toform layers, especially dielectric layers, based on metal oxides and/ormetal nitrides. Such deposition processes have included vapordeposition, metal thermal oxidation, and high vacuum sputtering. Vapordeposition processes, which include chemical vapor deposition (CVD) andatomic layer deposition (ALD) are very appealing, as they provide forexcellent control of dielectric uniformity and thickness on a substrate.

SUMMARY OF THE INVENTION

In view of the foregoing, and despite improvements in semiconductordielectric layers, there remains a need in the semiconductor art a vapordeposition process utilizing sufficiently volatile metal precursorcompounds that can form a thin, high quality oxide layers on asubstrate, particularly on a semiconductor substrate, using a vapordeposition process, particularly chemical vapor deposition (CVD) processand/or an atomic layer deposition (ALD) process.

Accordingly, the present invention is directed to methods and precursorcompositions useful for CVD and ALD processes. In one aspect, thepresent invention is directed to: a method of forming a metal-containinglayer on a substrate, the method including: providing a substrate;providing a precursor composition comprising at least one compound ofthe formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is XR³ or YR³R⁴,wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³ isindependently an organic group; R⁴ is hydrogen or an organic group; L isan anionic supporting ligand; n is the oxidation state of M; and x is 0to n-1; vaporizing the precursor composition; and contacting thevaporized precursor composition to form a metal-containing layer on thesubstrate using a vapor deposition process.

In a further aspect, the present invention is directed to a method ofmanufacturing a semiconductor structure, the method including: providinga semiconductor substrate or substrate assembly; providing at least oneprecursor compound of the formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is XR³ or YR³R⁴,wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³ isindependently an organic group; R⁴ is hydrogen or an organic group; L isan anionic supporting ligand; n is the oxidation state of M; and x is 0to n-1; providing at least one reaction gas; vaporizing the precursorcompound of Formula I; and contacting the vaporized precursor compoundof Formula I and the reaction gas with the substrate to form ametal-containing layer on the semiconductor substrate or substrateassembly using a vapor deposition process.

In yet another aspect, the present invention is directed to a method ofmanufacturing a semiconductor structure, the method including: providinga semiconductor substrate or substrate assembly within a depositionchamber; providing a vapor comprising at least one precursor compound ofthe formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is XR³ or YR³R⁴,wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³ isindependently an organic group; R⁴ is hydrogen or an organic group; L isan anionic supporting ligand; n is the oxidation state of M; and x is 0to n-1; directing the vapor including the at least one precursorcompound of Formula I to the semiconductor substrate or substrateassembly and allowing the at least one compound to chemisorb to at leastone surface of the semiconductor substrate or substrate assembly;providing at least one reaction gas; and directing the at least onereaction gas to the semiconductor substrate or substrate assembly withthe chemisorbed species thereon to form a metal-containing layer on atleast one surface of the semiconductor substrate or substrate assembly.

In still a further aspect, the present invention is directed to a methodof manufacturing a memory device structure, the method including:providing a substrate having a first electrode thereon; providing atleast one precursor compound of the formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is XR³ or YR³R⁴,wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³ isindependently an organic group; R⁴ is hydrogen or an organic group; L isan anionic supporting ligand; n is the oxidation state of M; and x is 0to n-1; vaporizing the at least one precursor compound of Formula I;contacting the at least one vaporized precursor compound of Formula Iwith the substrate to chemisorb the compound on the first electrode ofthe substrate; providing at least one reaction gas; contacting the atleast one reaction gas with the substrate with the chemisorbed compoundthereon to form a dielectric layer on the first electrode of thesubstrate; and forming a second electrode on the dielectric layer.

The present invention additionally is directed to apparatus useful forvapor deposition processes, preferably atomic layer depositionprocesses, as described herein. To this end, the present invention isfurther directed to a vapor deposition apparatus including: a depositionchamber having a substrate positioned therein; and at least one vesselincluding at least one precursor compound of the formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is XR³ or YR³R⁴,wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³ isindependently an organic group; R⁴ is hydrogen or an organic group; L isan anionic supporting ligand; n is the oxidation state of M; and x is 0to n-1.

The present invention is additionally directed to certain precursorcompositions useful for vapor deposition processes and disclosed herein.In one such embodiment, the present invention is directed to a precursorcomposition for use in a vapor deposition process including at least onecompound of the formula (Formula I):

wherein: M is selected from the group of a Group 2 to Group 15 metal, alanthanide, an actinide, and combinations thereof; E is OR³; each R¹,R², and R³ is independently an organic group; L is an anionic supportingligand; n is the oxidation state of M; and x is 0 to n-1.

In another embodiment, the present invention is directed to a precursorcomposition for use in a vapor deposition process including at least onecompound of the formula (Formula I):

wherein: M is lanthanum; E is XR³ or YR³R⁴, wherein X is O, S, or Se,and Y is N or P; each R¹, R², and R³ is independently an organic group;R⁴ is hydrogen or an organic group; L is an anionic supporting ligand; nis the oxidation state of M; and x is 0 to n-1.

In yet a further embodiment, the present invention is directed to aprecursor composition for use in a vapor deposition process including atleast one compound of the formula (Formula I):

wherein: M is hafnium; E is XR³ or YR³R⁴, wherein X is O, S, or Se, andY is N or P; R¹ and R² are isopropyl groups, R³ is an organic group; R⁴is hydrogen or an organic group; L is an anionic supporting ligand; n isthe oxidation state of M; and x is 0 to n-1.

Metal-organic complexes containing chelating ligands (e.g., two or moreatoms on each ligand coordinate to the metal atom) often show improvedstability compared to metal-organic compounds with unidentate ligandsand may be useful in deposition processes, provided such compounds haveadequate volatility properties.

It has now been discovered that the use of homoleptic and heterolepticguanidinate, phosphoguanidinate, isoureate, thioisoureate, andselenoisoureate compounds are useful as precursor compositions for vapordeposition, preferably ALD processes. Such compounds provide thepotential advantage in, for example, an ALD process in that theprotonated ligand (e.g., formed in situ after chemical adsorption to asurface) may be expected to decompose to carbodiimide and amine (fromguanidinate), to phosphine (from phosphoguanidinate), to alcohol (from(isoureate), to thiol (from thioisoureate), or to selenol (fromselenoisoureate). These fragments are believed to be more volatile thanthe parent ligands and should, thus, leave less carbon contamination inthe films.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a vapor deposition coating systemsuitable for use in the method of the present invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present invention includes methods of forming a metal containinglayer, preferably a metal oxide layer or a metal nitride layer, on asubstrate. Further, such metal containing layer is preferably formed ona semiconductor substrate or substrate assembly in the manufacture of asemiconductor structure or another memory device structure. Such layersare deposited or chemisorbed onto a substrate and form, preferably,dielectric layers. The methods of the present invention involve forminga layer on a substrate by using one or more metal precursor compounds ofthe formula (Formula I):

wherein: M is a Group 2 to Group 15 metal, a lanthanide, an actinide,and combinations thereof; E is XR³ or YR³R⁴, wherein X is O, S, or Se,preferably O or S, and Y is N or P; each R¹, R², and R³ is independentlyan organic group (as described in greater detail below); R⁴ is hydrogenor an organic group; L is an anionic supporting ligand; n is theoxidation state of M; and x is 0 to n-1. Preferred ligands, L, includehalides, amides, alkoxides, amidoxylates, amidinates, amidates,carboxylates, beta-diketonates, beta-imineketones, beta-diketiminates,carbonylates, ketiminates, and combinations thereof.

As used herein, the term “organic group” is used for the purpose of thisinvention to mean a hydrocarbon group that is classified as an aliphaticgroup, cyclic group, or combination of aliphatic and cyclic groups(e.g., alkaryl and aralkyl groups). In the context of the presentinvention, suitable organic groups for precursor compounds of thisinvention are those that do not interfere with the formation of a metaloxide layer using vapor deposition techniques. In the context of thepresent invention, the term “aliphatic group” means a saturated orunsaturated linear or branched hydrocarbon group. This term is used toencompass alkyl, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated linear or branched monovalenthydrocarbon group including, for example, methyl, ethyl, n-propyl,isopropyl, t-butyl, amyl, heptyl, and the like. The term “alkenyl group”means an unsaturated, linear or branched monovalent hydrocarbon groupwith one or more olefinically unsaturated groups (i.e., carbon-carbondouble bonds), such as a vinyl group. The term “alkynyl group” means anunsaturated, linear or branched monovalent hydrocarbon group with one ormore carbon-carbon triple bonds. The term “cyclic group” means a closedring hydrocarbon group that is classified as an alicyclic group,aromatic group, or heterocyclic group. The term “alicyclic group” meansa cyclic hydrocarbon group having properties resembling those ofaliphatic groups. The term “aromatic group” or “aryl group” means amono- or polynuclear aromatic hydrocarbon group. The term “heterocyclicgroup” means a closed ring hydrocarbon in which one or more of the atomsin the ring is an element other than carbon (e.g., nitrogen, oxygen,sulfur, etc.). For example, certain preferred organic groups includecyclic polyethers, polyamines, aromatic groups, heterocyclic groups,etc.

As a means of simplifying the discussion and the recitation of certainterminology used throughout this application, the terms “group” and“moiety” are used to differentiate between chemical species that allowfor substitution or that may be substituted and those that do not soallow for substitution or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withnonperoxidic O, N, S, Si, or F atoms, for example, in the chain as wellas carbonyl groups or other conventional substituents. Where the term“moiety” is used to describe a chemical compound or substituent, only anunsubstituted chemical material is intended to be included. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also alkyl substituents bearing furthersubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group”includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like.

The precursor compounds described herein may include a wide variety ofmetals. As used herein, “metal” includes all metals of the periodictable (including main group metals, transition metals, lanthanides,actinides, and metalloid such as B, Al, Ge, Si, As, Sb, Te, Po, At,etc.). For certain methods of the present invention, preferably, eachmetal M is selected from the group of metals of Groups 2-15, thelanthanides, the actinides of the Periodic Chart, and combinationsthereof. Preferably, for metal-oxide layers, M is selected from thegroup of Groups 3-5, Group 13, the lanthanides, and combinationsthereof. More preferably, M is selected from the group of Hf, Zr, Al,La, Pr, and combinations thereof.

Additionally, E is (XR³) or (YR³R⁴), with X being O, S, or Se, Y being Nor P, and R¹, R², R³, and R⁴ of Formula I being each independently anorganic group, and with R⁴ optionally being hydrogen. Preferably, eachof the organic groups of R¹, R², R³, and R⁴ contain 1-10 carbon atoms,more preferably, 1-6 carbon atoms, and most preferably, 1-4 carbonatoms. Preferred R groups include isopropyl groups.

Additionally, each of the organic groups R¹, R², R³, and R⁴ mayoptionally include one or more heteroatoms (e.g., oxygen, nitrogen,fluorine, etc.), or functional groups (e.g., carbonyl groups,hydroxycarbyl groups, aminocarbyl groups, alcohols, fluorinatedalcohols, etc.), provided that the heteroatoms are not directly bondedto hydrogen. That is, included within the scope of the compounds ofFormula I are compounds wherein at least one atom in the organic grouphas been replaced with, for example, one of a carbonyl group, ahydroxycarbyl group, an oxygen atom, a nitrogen atom, or an aminocarbylgroup. Certain preferred organic groups, R¹, R², R³, and R⁴, of FormulaI include (C1-C4) alkyl groups, which may be linear, branched, or cyclicgroups, as well as alkenyl groups (e.g., dienes and trienes), or alkynylgroups. An example of a preferred precursor compound of Formula I is:La((iPrN)₂CNEt₂)₃, wherein iPr is isopropyl and Et is ethyl.

The terms “substrate,” “semiconductor substrate,” or “substrateassembly” as used herein refer to either a substrate or a semiconductorsubstrate, such as a base semiconductor layer or a semiconductorsubstrate having one or more layers, structures, or regions formedthereon. A base semiconductor layer is typically the lowest layer ofsilicon material on a wafer or a silicon layer deposited on anothermaterial, such as silicon on sapphire. When reference is made to asubstrate assembly, various process steps may have been previously usedto form or define regions, junctions, various structures or features,and openings such as transistors, active areas, diffusions, implantedregions, vias, contact openings, high aspect ratio openings, capacitorplates, barriers for capacitors, etc.

“Layer,” as used herein, refers to any layer that can be formed on asubstrate from one or more precursors and/or reactants according to thedeposition process described herein. The term “layer” is meant toinclude layers specific to the semiconductor industry, such as, butclearly not limited to, a barrier layer, dielectric layer, andconductive layer. The term “layer” is synonymous with the term “film”frequently used in the semiconductor industry. The term “layer” is alsomeant to include layers found in technology outside of semiconductortechnology, such as coatings on glass. For example, such layers can beformed directly on fibers, wires, etc., which are substrates other thansemiconductor substrates. Further, the layers can be formed directly onthe lowest semiconductor surface of the substrate, or they can be formedon any of a variety of layers (e.g., surfaces) as in, for example, apatterned wafer.

“Dielectric layer” as used herein refers to a layer (or film) having ahigh dielectric constant containing primarily, for example, siliconoxides, zirconium oxides, aluminum oxides, tantalum oxides, titaniumoxides, niobium oxides, hafnium oxides, an oxide of a lanthanide, orcombinations thereof.

The terms “deposition process” and “vapor deposition process” as usedherein refer to a process in which a metal-containing layer is formed onone or more surfaces of a substrate (e.g., a doped polysilicon wafer)from vaporized precursor compound(s). Specifically, one or moreprecursor compounds are vaporized and directed to and/or contacted withone or more surfaces of a heated substrate (e.g., semiconductorsubstrate or substrate assembly) placed in a deposition chamber. Theseprecursor compounds form (e.g., by reacting or decomposing) anon-volatile, thin, uniform, metal-containing layer on the surface(s) ofthe substrate. For the purposes of this invention, the term “vapordeposition process” is meant to include both chemical vapor depositionprocesses (including pulsed chemical vapor deposition processes) andatomic layer deposition processes.

“Chemical vapor deposition” (CVD) as used herein refers to a vapordeposition process wherein the desired layer is deposited on thesubstrate from vaporized metal precursor compounds (and any reactiongases used) within a deposition chamber with no effort made to separatethe reaction components. In contrast to a “simple” CVD process thatinvolves the substantial simultaneous use of the precursor compounds andany reaction gases, “pulsed” CVD alternately pulses these materials intothe deposition chamber, but does not rigorously avoid intermixing of theprecursor and reaction gas streams, as is typically done in atomic layerdeposition or ALD (discussed in greater detail below).

The term “atomic layer deposition” (ALD) as used herein refers to avapor deposition process in which deposition cycles, preferably aplurality of consecutive deposition cycles, are conducted in a processchamber (i.e., a deposition chamber). Typically, during each cycle theprecursor is chemisorbed to a deposition surface (e.g., a substrateassembly surface or a previously deposited underlying surface such asmaterial from a previous ALD cycle). Thereafter, if necessary, areactant may subsequently be introduced into the process chamber for usein converting the chemisorbed precursor to the desired material on thedeposition surface. Further, purging steps may also be utilized duringeach cycle to remove excess precursor from the process chamber and/orremove excess reactant and/or reaction byproducts from the processchamber after conversion of the chemisorbed precursor. Further, the term“atomic layer deposition,” as used herein, is also meant to includeprocesses designated by related terms such as, “chemical vapor atomiclayer deposition”, “atomic layer epitaxy” (ALE) (see U.S. Pat. No.5,256,244 to Ackerman), molecular beam epitaxy (MBE), gas source MBE, ororganometallic MBE, and chemical beam epitaxy when performed withalternating pulses of precursor compound(s), reactive gas, and purge(e.g., inert carrier) gas.

As compared to the one cycle chemical vapor deposition (CVD) process,the longer duration multi-cycle ALD process allows for improved controlof layer thickness by self-limiting layer growth and minimizingdetrimental gas phase reactions by separation of the reactioncomponents.

“Precursor,” and “precursor compound” as used herein, refers to acompound usable for forming, either alone or with other precursorcompounds (or reactants), a layer on a substrate assembly in adeposition process. In one embodiment according to the presentinvention, the precursor includes a metal component and one or moreguanidinate, phosphoguanidinate, isoureate, thioisoureate, and/orselenoisoureate ligands. Further, one skilled in the art will recognizethat the precursor will depend on the content of a layer which isultimately to be formed using a vapor deposition process. The preferredprecursor compounds of the present invention are preferably liquid atthe vaporization temperature and, more preferably, are preferably liquidat room temperature.

The term “chemisorption” as used herein refers to the chemicaladsorption of vaporized reactive precursor compounds on the surface of asubstrate. The adsorbed species are typically irreversibly bound to thesubstrate surface as a result of relatively strong binding forcescharacterized by high adsorption energies (e.g., >30 kcal/mol),comparable in strength to ordinary chemical bonds. The chemisorbedspecies typically form a mononolayer on the substrate surface. (See “TheCondensed Chemical Dictionary”, 10th edition, revised by G. G. Hawley,published by Van Nostrand Reinhold Co., New York, 225 (1981)). Thetechnique of ALD is based on the principle of the formation of asaturated monolayer of reactive precursor molecules by chemisorption. InALD one or more appropriate precursor compounds or reaction gases arealternately introduced (e.g., pulsed) into a deposition chamber andchemisorbed onto the surfaces of a substrate. Each sequentialintroduction of a reactive compound (e.g., one or more precursorcompounds and one or more reaction gases) is typically separated by aninert carrier gas purge. Each precursor compound co-reaction adds a newatomic layer to previously deposited layers to form a cumulative solidlayer. The cycle is repeated, typically for several hundred times, togradually form the desired layer thickness. It should be understood thatALD can alternately utilize one precursor compound, which ischemisorbed, and one reaction gas, which reacts with the chemisorbedspecies.

Practically, chemisorption might not occur on all portions of thedeposition surface (e.g., previously deposited ALD material).Nevertheless, such imperfect monolayer is still considered a monolayerin the context of the present invention. In many applications, merely asubstantially saturated monolayer may be suitable. A substantiallysaturated monolayer is one that will still yield a deposited monolayeror less of material exhibiting the desired quality and/or properties.

“Reactant,” as used herein, may include another precursor or reactantgas useable according to the present invention in an ALD cycle. Forexample, to prepare a metal oxide layer, a reactant gas may include anoxidizing gas such as oxygen, water vapor, ozone, alcohol vapor,nitrogen oxide, sulfur oxide, hydrogen peroxide, and the like. Toprepare a metal-nitride layer, a reactant gas may include, for example,ammonia or amines (preferably primary amines). To prepare a pure metallayer, a reactant gas may include hydrogen, diborane or silane. However,such reactants may include any reactant(s) suitable for use inconverting the chemisorbed species present on the deposition surface aspart of an ALD cycle (e.g., provide a reducing atmosphere). As oneskilled in the art will recognize, such reactants will depend upon thelayer ultimately formed from the vapor deposition process.

“Inert gas,” or “non-reactive gas,” as used herein, is any gas that isgenerally unreactive with the components it comes in contact with. Forexample, inert gases are typically selected from a group includingnitrogen, argon, helium, neon, krypton, xenon, any other non-reactivegas, and mixtures thereof. Such inert gases are generally used in one ormore purging processes described according to the present invention.

“Purging,” according to the present invention, may involve a variety oftechniques including, but not limited to, contacting the substrateand/or monolayer(s) formed according to the present invention with acarrier gas (e.g., an inert gas), and/or lowering pressure to below thedeposition pressure to reduce the concentration of a species contactingthe substrate assembly surface and/or chemisorbed species. Purging mayalso include contacting the substrate assembly surface and/ormonolayer(s) formed thereon with any substance that allows chemisorptionbyproducts to desorb and reduces the concentration of a speciespreparatory to introducing another species. A suitable amount of purgingcan be determined experimentally, as known to those skilled in the art.Purging time may successively be reduced to a purge time that yieldsdesirable results, such as an increase in film growth rate.

The layers or films formed may be in the form of metal-containing films,such as reduced metals, metal silicates, metal oxides, metal nitrides,etc, as well as combinations thereof. For example, a metal oxide layermay include a single metal, or the metal oxide layer may include two ormore different metals (i.e., it is a mixed metal oxide) or a metal oxidelayer may optionally be doped with other metals.

If the metal oxide layer includes two or more different metals, themetal oxide layer can be in the form of alloys, solid solutions, ornanolaminates. Preferably, these have dielectric properties. The metaloxide layer (particularly if it is a dielectric layer) preferablyincludes one or more of HfO₂, ZrO₂, Al₂O₃, La₂O₃, and Pr₂O₃.Surprisingly, the metal oxide layer formed according to the presentinvention is essentially free of carbon. In addition, preferably thereduced metal layers formed by the systems and methods of the presentinvention are essentially free of carbon, hydrogen, halides, oxygen,phosphorus, sulfur, nitrogen, or compounds thereof. Additionally,preferably metal-oxide layers formed by the systems and methods of thepresent invention are essentially free of carbon, hydrogen, halides,phosphorus, sulfur, nitrogen or compounds thereof, and preferablymetal-nitride layers formed by the systems and methods of the presentinvention are essentially free of carbon, hydrogen, halides, oxygen,phosphorus, sulfur, or compounds thereof. As used herein, “essentiallyfree” is defined to mean that the metal-containing layer may include asmall amount of the above impurities. For example, for metal-oxidelayers, “essentially free” means that the above impurities are presentin an amount of less than about 1 percent (%) by weight, such that theyhave a minor effect on the chemical, mechanical, or electricalproperties of the film. Pure metal layers and metal-nitride layers, maytolerate a higher impurity content. For these layers, “essentially free”means that the above impurities are present in an amount of less thanabout 20% by weight.

In addition to the precursor compositions of Formula I, the presentinvention includes methods and apparatus in which a metal containingprecursor compound different that the precursor compound of Formula Imay be used. Such precursors may be deposited/chemisorbed, for examplein an ALD process discussed more fully below, substantiallysimultaneously with or sequentially to the precursor compounds ofFormula I.

Various precursor compounds can be used in various combinations,optionally with one or more organic solvents (particularly for CVDprocesses), to form a precursor composition. The precursor compounds maybe liquids or solids at room temperature (preferably, they are liquidsat the vaporization temperature). Typically, they are liquidssufficiently volatile to be employed using known vapor depositiontechniques. However, as solids they may also be sufficiently volatilethat they can be vaporized or sublimed from the solid state using knownvapor deposition techniques. If they are less volatile solids, they arepreferably sufficiently soluble in an organic solvent or have meltingpoints below their decomposition temperatures such that they can be usedin flash vaporization, bubbling, microdroplet formation techniques, etc.

Herein, vaporized precursor compounds may be used either alone oroptionally with vaporized molecules of other precursor compounds oroptionally with vaporized solvent molecules, if used. As used herein,“liquid” refers to a solution or a neat liquid (a liquid at roomtemperature or a solid at room temperature that melts at an elevatedtemperature). As used herein, “solution” does not require completesolubility of the solid but may allow for some undissolved solid, aslong as there is a sufficient amount of the solid delivered by theorganic solvent into the vapor phase for chemical vapor depositionprocessing. If solvent dilution is used in deposition, the total molarconcentration of solvent vapor generated may also be considered as ainert carrier gas.

Solvents that are suitable for certain embodiments of the presentinvention may be one or more of the following:aliphatic hydrocarbons orunsaturated hydrocarbons (C3-C20, and preferably C5-C10, cyclic,branched, or linear), aromatic hydrocarbons (C5-C20, and preferablyC5-C10), halogenated hydrocarbons, silylated hydrocarbons such asalkylsilanes, alkylsilicates, ethers, polyethers, thioethers, esters,lactones, nitrites, silicone oils, or compounds containing combinationsof any of the above or mixtures of one or more of the above. Thecompounds are also generally compatible with each other, so thatmixtures of variable quantities of the precursor compounds will notinteract to significantly change their physical properties.

The precursor compounds of the present invention can, optionally, bevaporized and deposited/chemisorbed substantially simultaneously with,and in the presence of, one or more reaction gases. Alternatively, themetal containing layers may be formed by alternately introducing theprecursor compound and the reaction gas(es) during each depositioncycle. Such reaction gases may typically include oxygen, water vapor,ozone, nitrogen oxides, sulfur oxides, hydrogen, hydrogen sulfide,hydrogen selenide, hydrogen telluride, hydrogen peroxide, ammonia,organic amine, silane, disilane and higher silanes, diborane, plasma,air, borazene (nitrogen source), carbon monoxide (reductant), alcohols,and any combination of these gases, noting that certain reaction gasesmay be more appropriate for certain metal-containing layers. Forexample, oxygen sources for the deposition of metal-oxide layers,nitrogen sources for deposition of metal-nitride layers, and reductantsfor deposition of reduced metal layers. Preferable optional reactiongases for metal-oxide layers include oxygen and ozone.

Suitable substrate materials of the present invention include conductivematerials, semiconductive materials, conductive metal-nitrides,conductive metals, etc. The substrate on which the metal containinglayer is formed is preferably a semiconductor substrate or substrateassembly. Any suitable semiconductor material is contemplated, such asfor example, borophosphosilicate glass (BPSG), silicon such as, e.g.,conductively doped polysilicon, monocrystalline silicon, etc. (for thisinvention, appropriate forms of silicon are simply referred to as“silicon”), for example in the form of a silicon wafer,tetraethylorthosilicate (TEOS) oxide, spin on glass (i.e., a thin layerof SiO₂, optionally doped, deposited by a spin on process), TiN, TaN, W,Ru, Al, Cu, noble metals, etc. A substrate assembly may also contain alayer that includes platinum, iridium, rhodium, ruthenium, rutheniumoxide, titanium nitride, tantalum nitride, tantalum-silicon-nitride,silicon dioxide, aluminum, gallium arsenide, glass, etc., and otherexisting or to-be-developed materials used in semiconductorconstructions, such as dynamic random access memory (DRAM) devices,static random access memory (SRAM) devices, and ferroelectric memory(FERAM) devices, for example.

For substrates including semiconductor substrates or substrateassemblies, the layers can be formed directly on the lowestsemiconductor surface of the substrate, or they can be formed on any ofa variety of the layers (i.e., surfaces) as in a patterned wafer, forexample.

Substrates other than semiconductor substrates or substrate assembliescan also be used in methods of the present invention. Any substrate thatmay advantageously form a metal containing layer thereon, such as ametal oxide layer, may be used, such substrates including, for example,fibers, wires, etc.

A preferred deposition process for the present invention is a vapordeposition process. Vapor deposition processes are generally favored inthe semiconductor industry due to the process capability to quicklyprovide highly conformal layers even within deep contacts and otheropenings.

The precursor compounds can be vaporized in the presence of an inertcarrier gas if desired. Additionally, an inert carrier gas can be usedin purging steps in an ALD process (discussed below). The inert carriergas is typically one or more of nitrogen, helium, argon, etc. In thecontext of the present invention, an inert carrier gas is one that doesnot interfere with the formation of the metal-containing layer. Whetherdone in the presence of a inert carrier gas or not, the vaporization ispreferably done in the absence of oxygen to avoid oxygen contaminationof the layer (e.g., oxidation of silicon to form silicon dioxide oroxidation of precursor in the vapor phase prior to entry into thedeposition chamber).

Chemical vapor deposition (CVD) and atomic layer deposition (ALD) aretwo vapor deposition processes often employed to form thin, continuous,uniform, metal-containing (preferably dielectric) layers ontosemiconductor substrates. Using either vapor deposition process,typically one or more precursor compounds are vaporized in a depositionchamber and optionally combined with one or more reaction gases anddirected to and/or contacted with the substrate to form ametal-containing layer on the substrate. It will be readily apparent toone skilled in the art that the vapor deposition process may be enhancedby employing various related techniques such as plasma assistance, photoassistance, laser assistance, as well as other techniques.

Chemical vapor deposition (CVD) has been extensively used for thepreparation of metal-containing layers, such as dielectric layers, insemiconductor processing because of its ability to provide highlyconformal and high quality dielectric layers at relatively fastprocessing times. Typically, the desired precursor compounds arevaporized and then introduced into a deposition chamber containing aheated substrate with optional reaction gases and/or inert carrier gasesin a single deposition cycle. In a typical CVD process, vaporizedprecursors are contacted with reaction gas(es) at the substrate surfaceto form a layer (e.g., dielectric layer). The single deposition cycle isallowed to continue until the desired thickness of the layer isachieved.

Typical CVD processes generally employ precursor compounds invaporization chambers that are separated from the process chamberwherein the deposition surface or wafer is located. For example, liquidprecursor compounds are typically placed in bubblers and heated to atemperature at which they vaporize, and the vaporized liquid precursorcompound is then transported by an inert carrier gas passing over thebubbler or through the liquid precursor compound. The vapors are thenswept through a gas line to the deposition chamber for depositing alayer on substrate surface(s) therein. Many techniques have beendeveloped to precisely control this process. For example, the amount ofprecursor material transported to the deposition chamber can beprecisely controlled by the temperature of the reservoir containing theprecursor compound and by the flow of an inert carrier gas bubbledthrough or passed over the reservoir.

A typical CVD process may be carried out in a chemical vapor depositionreactor, such as a deposition chamber available under the tradedesignation of 7000 from Genus, Inc. (Sunnyvale, Calif.), a depositionchamber available under the trade designation of 5000 from AppliedMaterials, Inc. (Santa Clara, Calif.), or a deposition chamber availableunder the trade designation of Prism from Novelus, Inc. (San Jose,Calif.). However, any deposition chamber suitable for performing CVD maybe used.

Several modifications of the CVD process and chambers are possible, forexample, using atmospheric pressure chemical vapor deposition, lowpressure chemical vapor deposition (LPCVD), plasma enhanced chemicalvapor deposition (PECVD), hot wall or cold wall reactors or any otherchemical vapor deposition technique. Furthermore, pulsed CVD can beused, which is similar to ALD (discussed in greater detail below) butdoes not rigorously avoid intermixing of precursor and reactant gasstreams. Also, for pulsed CVD, the deposition thickness is dependent onthe exposure time, as opposed to ALD, which is self-limiting (discussedin more detail below).

Alternatively, and preferably, the vapor deposition process employed inthe methods of the present invention is a multi-cycle atomic layerdeposition (ALD) process. Such a process is advantageous, in particularadvantageous over a CVD process, in that in provides for improvedcontrol of atomic-level thickness and uniformity to the deposited layer(e.g., dielectric layer) by providing a plurality of deposition cycles.Further, ALD processes typically expose the metal precursor compounds tolower volatilization and reaction temperatures, which tends to decreasedegradation of the precursor as compared to, for example, typical CVDprocesses.

Generally in an ALD process, each reactant is pulsed sequentially onto asuitable substrate, typically at deposition temperatures of at leastabout 25° C., preferably at least about 150° C., and more preferably atleast about 200° C. Typical deposition temperatures are no greater thanabout 400° C., preferably no greater than about 150° C., and even morepreferably no greater than about 250° C. These temperatures aregenerally lower than those presently used in CVD processes, whichtypically include deposition temperatures at the substrate surface of atleast about 150° C., preferably at least about 200° C., and morepreferably at least about 250° C. Typical deposition temperatures are nogreater than about 600° C., preferably no greater than about 500° C.,and even more preferably no greater than about 400° C. Under suchconditions the film growth is typically self-limiting (i.e., when thereactive sites on a surface are used up in an ALD process, thedeposition generally stops), insuring not only excellent conformalitybut also good large area uniformity plus simple and accurate thicknesscontrol. Due to alternate dosing of the precursor compounds and/orreaction gases, detrimental vapor-phase reactions are inherentlyeliminated, in contrast to the CVD process that is carried out bycontinuous coreaction of the precursors and/or reaction gases. (SeeVehkamäki et al, “Growth of SrTiO₃ and BaTiO₃ Thin Films by Atomic LayerDeposition,” Electrochemical and Solid-State Letters, 2(10):504-506(1999)).

A typical ALD process includes exposing an initial substrate to a firstchemical species A (e.g., a metal precursor compound such as that ofFormula I) to accomplish chemisorption of the species onto thesubstrate. Species A can react either with the substrate surface of withSpecies B (described below) but not with itself. Typically inchemisorption, one or more of the ligands of Species A is displaced byreactive groups on the substrate surface. Theoretically, thechemisorption forms a monolayer that is uniformly one atom or moleculethick on the entire exposed initial substrate, the monolayer beingcomposed of Species A, less any displaced ligands. In other words, asaturated monolayer is substantially formed on the substrate surface.Practically, chemisorption may not occur on all portions of thesubstrate. Nevertheless, such a partial monolayer is still understood tobe a monolayer in the context of the present invention. In manyapplications, merely a substantially saturated monolayer may besuitable. A substantially saturated monolayer is one that will stillyield a deposited layer exhibiting the quality and/or properties desiredfor such layer.

The first species (e.g., substantially all non-chemisorbed molecules ofSpecies A) as well as displaced ligands are purged from over thesubstrate and a second chemical species, Species B (e.g., a differentprecursor compound or reactant gas) is provided to react with themonolayer of Species A. Species B typically displaces the remainingligands from the Species A monolayer and thereby is chemisorbed andforms a second monolayer. This second monolayer displays a surface whichis reactive only to Species A. Non-chemisorbed Species B, as well asdisplaced ligands and other byproducts of the reaction are then purgedand the steps are repeated with exposure of the Species B monolayer tovaporized Species A. Optionally, the second species can react with thefirst species, but not chemisorb additional material thereto. That is,the second species can cleave some portion of the chemisorbed firstspecies, altering such monolayer without forming another monolayerthereon, but leaving reactive sites available for formation ofsubsequent monolayers. In other ALD processes, a third species or moremay be successively chemisorbed (or reacted) and purged just asdescribed for the first and second species, with the understanding thateach introduced species reacts with the monolayer produced immediatelyprior to its introduction. Optionally, the second species (or third orsubsequent) can include at least one reaction gas if desired.

Thus, the use of ALD provides the ability to improve the control ofthickness and uniformity of metal containing layers on a substrate. Forexample, depositing thin layers of precursor compound in a plurality ofcycles provides a more accurate control of ultimate film thickness. Thisis particularly advantageous when the precursor compound is directed tothe substrate and allowed to chemisorb thereon, preferably furtherincluding at least one reaction gas that reacts with the chemisorbedspecies on the substrate, and even more preferably wherein this cycle isrepeated at least once.

Purging of excess vapor of each species followingdeposition/chemisorption onto a substrate may involve a variety oftechniques including, but not limited to, contacting the substrateand/or monolayer with an inert carrier gas and/or lowering pressure tobelow the deposition pressure to reduce the concentration of a speciescontacting the substrate and/or chemisorbed species. Examples of carriergases, as discussed above, may include N₂, Ar, He, etc. Additionally,purging may instead include contacting the substrate and/or monolayerwith any substance that allows chemisorption by-products to desorb andreduces the concentration of a contacting species preparatory tointroducing another species. The contacting species may be reduced tosome suitable concentration or partial pressure known to those skilledin the art based on the specifications for the product of a particulardeposition process.

ALD is often described as a self-limiting process, in that a finitenumber of sites exist on a substrate to which the first species may formchemical bonds. The second species might only bond to the first speciesand thus may also be self-limiting. Once all of the finite number ofsites on a substrate are bonded with a first species, the first specieswill not bond to other of the first species already bonded with thesubstrate. However, process conditions can be varied in ALD to promotesuch bonding and render ALD not self-limiting, e.g., more like pulsedCVD. Accordingly, ALD may also encompass a species forming other thanone monolayer at a time by stacking of a species, forming a layer morethan one atom or molecule thick.

The described method indicates the “substantial absence” of the secondprecursor (i.e., second species) during chemisorption of the firstprecursor since insignificant amounts of the second precursor might bepresent. According to the knowledge and the preferences of those withordinary skill in the art, a determination can be made as to thetolerable amount of second precursor and process conditions selected toachieve the substantial absence of the second precursor.

Thus, during the ALD process, numerous consecutive deposition cycles areconducted in the deposition chamber, each cycle depositing a very thinmetal-containing layer (usually less than one monolayer such that thegrowth rate on average is from about 0.2 to about 3.0 Angstroms percycle), until a layer of the desired thickness is built up on thesubstrate of interest. The layer deposition is accomplished byalternately introducing (i.e., by pulsing) precursor compound(s) intothe deposition chamber containing a substrate, chemisorbing theprecursor compound(s) as a monolayer onto the substrate surfaces,purging the deposition chamber, then introducing to the chemisorbedprecursor compound(s) precursor compound(s) that may be the same as thefirst precursor compound(s) or may be other precursor compound(s) in aplurality of deposition cycles until the desired thickness of themetal-containing layer is achieved. Preferred thicknesses of the metalcontaining layers of the present invention are at least about 1 angstrom(Å), more preferably at least about 5 Å, and more preferably at leastabout 10 Å. Additionally, preferred film thicknesses are typically nogreater than about 500 Å, more preferably no greater than about 200 Å,and more preferably no greater than about 100 Å.

The pulse duration of precursor compound(s) and inert carrier gas(es) isgenerally of a duration sufficient to saturate the substrate surface.Typically, the pulse duration is at least about 0.1, preferably at leastabout 0.2 second, and more preferably at least about 0.5 second.Preferred pulse durations are generally no greater than about 5 seconds,and preferably no greater than about 3 seconds.

In comparison to the predominantly thermally driven CVD, ALD ispredominantly chemically driven. Thus, ALD may advantageously beconducted at much lower temperatures than CVD. During the ALD process,the substrate temperature may be maintained at a temperaturesufficiently low to maintain intact bonds between the chemisorbedprecursor compound(s) and the underlying substrate surface and toprevent decomposition of the precursor compound(s). The temperature, onthe other hand, must be sufficiently high to avoid condensation of theprecursor compounds(s). Typically the substrate temperature is keptwithin the range of about 25° C. to about 400° C. (preferably about 150°C. to about 300° C., and more preferably about 200° C. to about 250°C.), which, as discussed above, is generally lower than temperaturespresently used in typical CVD processes. Thus, the first species orprecursor compound is chemisorbed at this temperature. Surface reactionof the second species or precursor compound can occur at substantiallythe same temperature as chemisorption of the first precursor or,optionally but less preferably, at a substantially differenttemperature. Clearly, some small variation in temperature, as judged bythose of ordinary skill, can occur but still be considered substantiallythe same temperature by providing a reaction rate statistically the sameas would occur at the temperature of the first precursor chemisorption.Alternatively, chemisorption and subsequent reactions could insteadoccur at substantially exactly the same temperature.

For a typical vapor deposition process, the pressure inside thedeposition chamber is at least about 10⁻⁶ torr, preferably at leastabout 10⁻⁵ torr, and more preferably at least about 10⁻⁴ torr. Further,deposition pressures are typically no greater than about 10 torr,preferably no greater than about 1 torr, and more preferably no greaterthan about 10⁻¹ torr. Typically, the deposition chamber is purged withan inert carrier gas after the vaporized precursor compound(s) have beenintroduced into the chamber and/or reacted for each cycle. The inertcarrier gas/gases can also be introduced with the vaporized precursorcompound/compounds during each cycle.

The reactivity of a precursor compound can significantly influence theprocess parameters in ALD. Under typical CVD process conditions, ahighly reactive compound may react in the gas phase generatingparticulates, depositing prematurely on undesired surfaces, producingpoor films, and/or yielding poor step coverage or otherwise yieldingnon-uniform deposition. For at least such reason, a highly reactivecompound might be considered not suitable for CVD. However, somecompounds not suitable for CVD are superior ALD precursors. For example,if the first precursor is gas phase reactive with the second precursor,such a combination of compounds might not be suitable for CVD, althoughthey could be used in ALD. In the CVD context, concern might also existregarding sticking coefficients and surface mobility, as known to thoseskilled in the art, when using highly gas-phase reactive precursors,however, little or no such concern would exist in the ALD context.

After layer formation on the substrate, an annealing process may beoptionally performed in situ in the deposition chamber in a nitrogenatmosphere or oxidizing atmosphere. Preferably, the annealingtemperature is at least about 400° C., more preferably at least about600° C. The annealing temperature is preferably no greater than about1000° C., more preferably no greater than about 750° C., and even morepreferably no greater than about 700° C.

The annealing operation is preferably performed for a time period of atleast about 0.5 minute, more preferably for a time period of at leastabout 1 minute. Additionally, the annealing operation is preferablyperformed for a time period of no greater than about 60 minutes, andmore preferably for a time period of no greater than about 10 minutes.

One skilled in the art will recognize that such temperatures and timeperiods may vary. For example, furnace anneals and rapid thermalannealing may be used, and further, such anneals may be performed in oneor more annealing steps.

As stated above, the use of the complexes and methods of forming filmsof the present invention are beneficial for a wide variety of thin filmapplications in semiconductor structures, particularly those using highdielectric materials. For example, such applications include gatedielectrics and capacitors such as planar cells, trench cells (e.g.,double sidewall trench capacitors), stacked cells (e.g., crown, V-cell,delta cell, multi-fingered, or cylindrical container stackedcapacitors), as well as field effect transistor devices.

A system that can be used to perform vapor deposition processes(chemical vapor deposition or atomic layer deposition) of the presentinvention is shown in FIG. 1. The system includes an enclosed vapordeposition chamber 10, in which a vacuum may be created using turbo pump12 and backing pump 14. One or more substrates 16 (e.g., semiconductorsubstrates or substrate assemblies) are positioned in chamber 10. Aconstant nominal temperature is established for substrate 16, which canvary depending on the process used. Substrate 16 may be heated, forexample, by an electrical resistance heater 18 on which substrate 16 ismounted. Other known methods of heating the substrate may also beutilized.

In this process, precursor compound(s) (such as the precursor compoundof Formula I) 60 and/or 61 are stored in vessels 62. The precursorcompound(s) are vaporized and separately fed along lines 64 and 66 tothe deposition chamber 10 using, for example, an inert carrier gas 68. Areaction gas 70 may be supplied along line 72 as needed. Also, a purgegas 74, which is often the same as the inert carrier gas 68, may besupplied along line 76 as needed. As shown, a series of valves 80-85 areopened and closed as required.

The following examples are offered to further illustrate variousspecific embodiments and techniques of the present invention. It shouldbe understood, however, that many variations and modificationsunderstood by those of ordinary skill in the art may be made whileremaining within the scope of the present invention. Therefore, thescope of the invention is not intended to be limited by the followingexample. Unless specified otherwise, all percentages shown in theexamples are percentages by weight.

EXAMPLES Example 1 Synthesis and Characterization of a HomolepticPrecursor Compound of Formula I, where M=La, n=3, x=0, R¹═R²═CH(CH₃)₂,E=N(CH₂CH₃)₂

In a dry box, a Schlenk flask was charged with 1.187 grams (g) lithiumdiethylamide and approximately 100 milliliters (mL) tetrahydrofuran(THF). The flask was placed under a vacuum and 2.35 mL ofN,N′-diisopropylcarbodiimide was added via syringe through a rubberseptum. The solution was stirred for approximately 3 hours (h).

A second Schlenk flask was charged in the dry box with 4.044 gLaI₃(thf)₄ and approximately 100 mL THF and the flask was placed under avacuum. Lithium guanidinate solution was added slowly to the LaI₃ slurryover a period of approximately 3 hours then was stirred overnight underan argon atmosphere. Volatiles were stripped off in vacuo and theresulting oily amber solid was triturated with 2×5 mL pentane topartially remove coordinated THF. Volatiles were stripped off after eachtrituration and the solid became less oily. Also, a white solid waspartially separated from the amber material. Crude solid (6.558 g) wascollected under an argon atmosphere and charged into a sublimationvessel. Heating to 110° C. at 40 milliTorr (mTorr) produced an off-whitecrystalline solid sublimate. Under these conditions, 1.510 g of materialwas recovered (41% yield). Characterization data: ICP (elementalanalysis)-% La found (calculated) 19.5 (18.9); TOF-MS-parent peak notseen, but the highest mass peak (201) consistent with ligand ion mass(199) and fragment peaks match expected fragmentation pattern of ligand;¹H NMR (C6D6) δ3.64 (septet, J=6.3 Hz, 6H, N—CH(CH₃)₂), 2.97 (b, 12H,N—CH₂—CH₃), 1.39 (b, 36H, N—CH(CH₃)₂), 0.98 (t, J=7 Hz, 18H, N—CH₂—CH₃);IR—moderate absorption at 1620 cm⁻¹, consistent with C═N stretchingmode.

Example 2 Synthesis and Characterization of a Heteroleptic PrecursorCompound of Formula I, where M=Hf, n=4, x=2, R¹═R²═CH(CH₃)₂, E=N(CH₃)₂,L=N(CH₃)₂

In a dry box, a Schlenk flask was charged with 50 mL pentane and 7.7 mL46% hafnium tetrakis(dimethylamide) in pentane. This flask was adaptedto a vacuum/argon manifold and 3.1 mL of N,N′-diisopropylcarbodiimidewas added dropwise at room temperature through argon overpressure. Amild exotherm and refluxing pentane was observed.

The reaction solution was stirred for four hours, then volatiles wereremoved in vacuo, affording 5.3 g of an off-white solid. The crudematerial was sublimed twice to afford a total yield of 3.74 g ofanalytically pure title compound (61% yield). The material was a white,crystalline solid.

Characterization data: ICP % Hf found (calculated) 29.8 (29.4); TOF-MSlargest mass peak 569 amu, consistent with mass of parent compound lessa dimethylamide ligand, other peaks consistent with other expectedfragmentation products; ¹H NMR (C6D6) δ 3.75(b, 4H, NCH(CH₃)₂), 3.39 (s,12H, HfN(CH₃)₂), 2.52 (s, 12H, CN(CH₃)₂), 1.28 (b, 24H, NCH(CH₃)₂).

Example 3 Synthesis and Characterization of a Heteroleptic PrecursorCompound of Formula I, where M=Hf, n=4, x=2, R¹═R²═CH(CH₃)₂, E=OCH₃,L=N(CH₃)₂

In a dry box, a Schlenk flask was charged with 200 mL pentane and 10.2 g52% hafnium tetrakis(dimethylamide) in pentane. This flask was adaptedto a vacuum/argon manifold and 5.5 mL ofO-methyl-N,N′-diisopropylisourea was added dropwise at room temperaturethrough argon overpressure. Bubbling was observed, indicating themetathetical formation of volatile dimethylamine.

After 16 hours, the volatiles were removed in vacuo, affording a whitepaste. This crude product was sublimed at 105° C. and 50 mTorr to afforda white solid sublimate (1.05 g, 12% yield). Characterization data: ICP% Hf found (calculated) 31.5 (30.7).

Example 4 Deposition of a Precursor Composition of Formula I by AtomicLayer Deposition

The precursor from example 2 was used in a CVD process to prepare ametal-containing layer on a bare silicon wafer substrate. The precursorbubbler was heated to 140° C., and bubbler line to 180° C. Heliumcarrier gas at 39 sccm was passed over the bubbler and into thedeposition chamber where the wafer was sitting on a chuck heated to 315°C. A stream of ozone (11% by weight in molecular oxygen) at 25 sccm wassimultaneously introduced into the chamber. Both precursor and ozonewere introduced for a period of three minutes. Upon removing thesubstrate from the chamber, a film was visually observed to have formed.X-ray diffraction (XRD) analysis showed peaks at 31, 35.5, and 51.5degrees, indicating the formation of a hafnium-oxide-nitride film.

The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

1. A method of forming a metal-containing layer on a substrate, themethod comprising: providing a substrate; providing a precursorcomposition comprising at least one compound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 to Group15 metal, a lanthanide, an actinide, and combinations thereof; E is XR³or YR³R⁴, wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³is independently an organic group; R⁴ is hydrogen or an organic group; Lis an anionic supporting ligand; n is the oxidation state of M; and x is0 to n-1; vaporizing the precursor composition; and contacting thevaporized precursor composition to form a metal-containing layer on thesubstrate using a vapor deposition process.
 2. The method of claim 1wherein X is oxygen or sulphur.
 3. The method of claim 1 wherein theorganic group is selected from the group consisting of an alkyl group,an aliphatic group, a cyclic group, and combinations thereof.
 4. Themethod of claim 1 wherein L is selected from the group consisting ofhalides, amides, alkoxides, amidoxylates, amidinates, amidates,carboxylates, beta-diketonates, beta-imineketones, beta-diketiminates,carbonylates, ketiminates, and combinations thereof.
 5. The method ofclaim 1 wherein M is selected from the group consisting of Group 3 toGroup 5 metals, Group 13 metals, lanthanides, and combinations thereof.6. The method of claim 5 wherein M is selected from the group consistingof Hf, Zr, Al, La, Pr, and combinations thereof.
 7. The method of claim1 wherein the metal-containing layer is a metal-oxide layer.
 8. Themethod of claim 1 wherein the metal-containing layer is a metal-nitridelayer.
 9. The method of claim 1 wherein the substrate is selected fromthe group consisting of a semiconductive material, a conductivematerial, a conductive metal-nitride, a conductive metal, andcombinations thereof.
 10. The method of claim 1 wherein themetal-containing layer has a thickness of about 1 angstrom to about 500angstroms.
 11. The method of claim 1 wherein R⁴ is hydrogen.
 12. Themethod of claim 1 wherein the organic group independently comprises 1 to10 carbon atoms.
 13. The method of claim 12 wherein the organic groupindependently comprises 1 to 4 carbon atoms.
 14. The method of claim 1wherein the vapor deposition process is a chemical vapor depositionprocess.
 15. The method of claim 1 wherein the vapor deposition processis an atomic layer deposition process comprising a plurality ofdeposition cycles.
 16. A method of manufacturing a semiconductorstructure, the method comprising: providing a semiconductor substrate orsubstrate assembly; providing at least one precursor compound of theformula (Formula I):

wherein: M is selected from the group consisting of a Group 2 to Group15 metal, a lanthanide, an actinide, and combinations thereof; E is XR³or YR³R⁴, wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³is independently an organic group; R⁴ is hydrogen or an organic group; Lis an anionic supporting ligand; n is the oxidation state of M; and x is0 to n-1; providing at least one reaction gas; vaporizing the precursorcompound of Formula I; and contacting the vaporized precursor compoundof Formula I and the reaction gas with the substrate to form ametal-containing layer on the semiconductor substrate or substrateassembly using a vapor deposition process.
 17. The method of claim 16wherein X is oxygen or sulfur.
 18. The method of claim 16 wherein theorganic group is selected from the group consisting of an alkyl group,an aliphatic group, a cyclic group, and combinations thereof.
 19. Themethod of claim 16 wherein R⁴ is hydrogen.
 20. The method of claim 16wherein L is selected from the group consisting of halides, amides,alkoxides, amidoxylates, amidinates, amidates, carboxylates,beta-diketonates, beta-imineketones, beta-diketiminates, carbonylates,ketiminates, and combinations thereof.
 21. The method of claim 16wherein the metal-containing layer is a metal-oxide layer.
 22. Themethod of claim 16 wherein the metal-containing layer is a metal-nitridelayer.
 23. The method of claim 22 wherein the metal oxide layer is adielectric layer.
 24. The method of claim 16 wherein themetal-containing layer is a metal-nitride layer.
 25. The method of claim16 wherein M is selected from the group consisting of Group 3 to Group 5metals, Group 13 metals, lanthanides, and combinations thereof.
 26. Themethod of claim 25 wherein M is selected from the group consisting ofHf, Zr, Al, La, Pr, and combinations thereof.
 27. The method of claim 16wherein the metal oxide layer has a thickness of about 1 angstrom toabout 500 angstroms.
 28. The method of claim 16 wherein the organicgroup independently comprises 1 to 10 carbon atoms.
 29. The method ofclaim 28 wherein the organic group independently comprises 1 to 4 carbonatoms.
 30. The method of claim 16 wherein the at least one reaction gasis selected from the group consisting of oxygen, water vapor, ozone,nitrogen oxides, sulfur oxides, hydrogen, hydrogen sulfide, hydrogenselenide, hydrogen telluride, hydrogen peroxide, ammonia, organic amine,silane, disilane and higher silanes, diborane, plasma, air, borazene,carbon monoxide, alcohols, and combinations thereof.
 31. The method ofclaim 16 further comprising an inert gas selected from the groupconsisting of nitrogen, argon, helium, and combinations thereof.
 32. Themethod of claim 16 wherein the substrate is selected from the groupconsisting of a semiconductive material, a conductive material, aconductive metal-nitride, a conductive metal, and combinations thereof.33. The method of claim 32 wherein the substrate is selected from thegroup of undoped silicon, doped silicon, borophosphosilicate glass(BPSG), tetraethylorthosilicate oxide (TEOS), TiN, TaN, GaAs, SiO₂, RuO,TaSiN, Pt, Ir, Rh, Ru, Al, Cu, W, and combinations thereof.
 34. Themethod of claim 16 wherein the vapor deposition process is a chemicalvapor deposition process.
 35. The method of claim 34 wherein thetemperature of the semiconductor substrate or substrate assembly isabout 150° C. to about 600° C.
 36. The method of claim 31 wherein thesemiconductor substrate or substrate assembly is in a deposition chamberthat has a pressure of about 10⁻⁶ torr to about 10 torr.
 37. The methodof claim 16 wherein the vapor deposition process is an atomic layerdeposition process comprising a plurality of deposition cycles.
 38. Themethod of claim 37 wherein during the atomic layer deposition processthe metal-containing layer is formed by alternately introducing thevaporized precursor compound of Formula I and the reaction gas duringeach deposition cycle.
 39. The method of claim 37 wherein thetemperature of the semiconductor substrate or substrate assembly isabout 25° C. to about 400° C.
 40. The method of claim 34 wherein thesemiconductor substrate or substrate assembly is in a deposition chamberthat has a pressure of about 10⁻⁶ torr to about 10 torr.
 41. A method ofmanufacturing a semiconductor structure, the method comprising:providing a semiconductor substrate or substrate assembly within adeposition chamber; providing a vapor comprising at least one precursorcompound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 to Group15 metal, a lanthanide, an actinide, and combinations thereof; E is XR³or YR³R⁴, wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³is independently an organic group; R⁴ is hydrogen or an organic group; Lis an anionic supporting ligand; n is the oxidation state of M; and x is0 to n-1; directing the vapor comprising the at least one precursorcompound of Formula I to the semiconductor substrate or substrateassembly and allowing the at least one compound to chemisorb to at leastone surface of the semiconductor substrate or substrate assembly;providing at least one reaction gas; and directing the at least onereaction gas to the semiconductor substrate or substrate assembly withthe chemisorbed species thereon to form a metal-containing layer on atleast one surface of the semiconductor substrate or substrate assembly.42. The method of claim 41 wherein X is oxygen or sulfur.
 43. The methodof claim 41 wherein the organic group is selected from the groupconsisting of an alkyl group, an aliphatic group, a cyclic group, andcombinations thereof.
 44. The method of claim 41 wherein L is selectedfrom the group consisting of halides, amides, alkoxides, amidoxylates,amidinates, amidates, carboxylates, beta-diketonates, beta-imineketones,beta-diketiminates, carbonylates, ketiminates, and combinations thereof.45. The method of claim 41 wherein the metal-containing layer is ametal-oxide layer.
 46. The method of claim 41 wherein themetal-containing layer is a metal-nitride layer.
 47. The method of claim41 wherein providing a vapor comprising at least one precursor compoundof Formula I, directing the vapor to the semiconductor substrate orsubstrate assembly, providing at least one reaction gas, and directingthe at least one reaction gas to the semiconductor substrate orsubstrate assembly is repeated at least once.
 48. The method of claim 41wherein the at least one reaction gas is selected from the groupconsisting of oxygen, water vapor, ozone, nitrogen oxides, sulfuroxides, hydrogen, hydrogen sulfide, hydrogen selenide, hydrogentelluride, hydrogen peroxide, ammonia, organic amine, silane, disilaneand higher silanes, diborane, plasma, air, borazene, carbon monoxide,alcohols, and combinations thereof.
 49. The method of claim 41 whereinthe metal-containing layer has a thickness of about 1 angstrom to about500 angstroms.
 50. The method of claim 41 wherein the temperature of thesemiconductor substrate or substrate assembly is about 25° C. to about400° C.
 51. The method of claim 41 wherein the deposition chambercontaining the semiconductor substrate or substrate assembly has apressure of about 10⁻⁶ torr to about 10 torr.
 52. The method of claim 41further comprising purging excess vapor comprising the at least oneprecursor compound of Formula I from the deposition chamber afterchemisorption of the compound onto the semiconductor substrate orsubstrate assembly.
 53. The method of claim 52 wherein purging comprisespurging with an inert gas.
 54. The method of claim 53 wherein the inertgas is selected from the group consisting of nitrogen, helium, argon,and combinations thereof.
 55. A method of manufacturing a memory devicestructure, the method comprising; providing a substrate having a firstelectrode thereon; providing at least one precursor compound of theformula (Formula I):

wherein: M is selected from the group consisting of a Group 2 to Group15 metal, a lanthanide, an actinide, and combinations thereof; E is XR³or YR³R⁴, wherein X is O, S, or Se, and Y is N or P; each R¹, R², and R³is independently an organic group; R⁴ is hydrogen or an organic group; Lis an anionic supporting ligand; n is the oxidation state of M; and x is0 to n-1; vaporizing the at least one precursor compound of Formula I;contacting the at least one vaporized precursor compound of Formula Iwith the substrate to chemisorb the compound on the first electrode ofthe substrate; providing at least one reaction gas; contacting the atleast one reaction gas with the substrate with the chemisorbed compoundthereon to form a dielectric layer on the first electrode of thesubstrate; and forming a second electrode on the dielectric layer.
 56. Aprecursor composition for use in a vapor deposition process comprisingat least one compound of the formula (Formula I):

wherein: M is selected from the group consisting of a Group 2 to Group15 metal, a lanthanide, an actinide, and combinations thereof; E is OR³;each R¹, R², and R³ is independently an organic group; L is an anionicsupporting ligand; n is the oxidation state of M; and x is 0 to n-1. 57.The precursor composition of claim 56 wherein the organic group isselected from the group consisting of an alkyl group, an aliphaticgroup, a cyclic group, and combinations thereof.
 58. The precursorcomposition of claim 56 wherein L is selected from the group consistingof halides, amides, alkoxides, amidoxylates, amidinates, amidates,carboxylates, beta-diketonates, beta-imineketones, beta-diketiminates,carbonylates, ketiminates, and combinations thereof.
 59. A precursorcomposition for use in a vapor deposition process comprising at leastone compound of the formula (Formula I):

wherein: M is lanthanum; E is XR³ or YR³R⁴, wherein X is O, S, or Se,and Y is N or P; each R¹, R², R³ is independently an organic group; R⁴is hydrogen or an organic group; L is an anionic supporting ligand; n isthe oxidation state of M; and x is 0 to n-1.
 60. The precursorcomposition of claim 59 wherein the organic group is selected from thegroup consisting of an alkyl group, an aliphatic group, a cyclic group,and combinations thereof.
 61. The precursor composition of claim 59wherein L is selected from the group consisting of halides, amides,alkoxides, amidoxylates, amidinates, amidates, carboxylates,beta-diketonates, beta-imineketones, beta-diketiminates, carbonylates,ketiminates, and combinations thereof.
 62. A precursor composition foruse in a vapor deposition process comprising at least one compound ofthe formula (Formula I):

wherein: M is hafnium; E is XR³ or YR³R⁴, wherein X is O, S, or Se, andY is N or P; R¹ and R² are isopropyl groups; R³ is an organic group; R⁴is hydrogen or an organic group; L is an anionic supporting ligand; n isthe oxidation state of M; and x is 0 to n-1.
 63. The precursorcomposition of claim 62 wherein the organic group is selected from thegroup consisting of an alkyl group, an aliphatic group, a cyclic group,and combinations thereof.
 64. The precursor composition of claim 62wherein L is selected from the group consisting of halides, amides,alkoxides, amidoxylates, amidinates, amidates, carboxylates,beta-diketonates, beta-imineketones, beta-diketiminates, carbonylates,ketiminates, and combinations thereof.